JP2017104840A - Semipermeable membrane support body and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semipermeable membrane support body that is excellent in adhesive property of a semipermeable membrane to a semipermeable membrane support body and prevents a semipermeable membrane solution from permeating to the rear side.SOLUTION: In the semipermeable membrane support body formed of a nonwoven fabric containing at least main synthetic fiber and binder synthetic fiber, molten whisker of the binder synthetic fiber is present at a surface on at least one side of the semipermeable membrane support body.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a semipermeable membrane support and a method for producing the same.

  Semipermeable membranes are widely used in the fields of seawater desalination, water purification, food concentration, wastewater treatment, medical fields represented by blood filtration, and ultrapure water production for semiconductor cleaning. . The semipermeable membrane is made of a synthetic resin such as a cellulose resin, a polysulfone resin, a polyacrylonitrile resin, a fluorine resin, or a polyester resin. However, since the semipermeable membrane itself is inferior in mechanical strength, a separation membrane in the form of a composite in which a semipermeable membrane is provided on one side of a semipermeable membrane support made of a fibrous base material such as a nonwoven fabric or a woven fabric is used. Has been. In this specification, the one surface on which the semipermeable membrane of the semipermeable membrane support is provided is referred to as “application surface”, and the opposite surface is referred to as “non-application surface”.

  Mainly, a nonwoven fabric containing synthetic fibers is used as the semipermeable membrane support. The performance required for the semipermeable membrane support includes good adhesion between the semipermeable membrane and the semipermeable membrane support, and the semipermeable membrane solution is used to provide the semipermeable membrane support. For example, the semipermeable membrane solution does not penetrate the non-coated surface when applied to the surface.

  In order to improve the uniformity of the semipermeable membrane support so that the semipermeable membrane solution does not pass through, in the step of wet papermaking a fiber slurry in which synthetic fibers are dispersed in water, The fiber slurry has a fiber content concentration of 0.01 to 0.1% by mass, and a water-soluble polymer having a molecular weight of 5 million or more is added to the fiber slurry as a polymer viscosity agent, based on the fiber content mass of 3 to 3%. A method of making paper by containing 15% by mass has been proposed (see, for example, Patent Document 1). However, since the polymer viscosity agent is added excessively, the uniformity is increased, but the fiber slurry viscosity on the papermaking wire is increased, the dewaterability from the wire is decreased, and the production rate cannot be increased. There could be a problem. In addition, there has been a problem that the polymer adhesive remains on the surface of the fibers forming the semipermeable membrane support after paper making.

  A multilayer nonwoven fabric based on a double structure consisting of a surface layer (thick fiber layer) having a large surface roughness using thick fibers and a back layer (thin fiber layer) having a dense structure using thin fibers. A semipermeable membrane support comprising the above has been proposed (see, for example, Patent Document 2). Specifically, a semipermeable membrane support having a thick fiber layer as the application surface and a thin fiber layer as the non-application surface, sandwiching the thin fiber layer with the thick fiber layer, and both the application surface and the non-application surface as a thick fiber layer A semipermeable membrane support is described. However, since thick fibers are used on the coated surface, the adhesion between the semipermeable membrane and the semipermeable membrane support is improved, but there is a problem that the smoothness is low. In addition, because thick fibers are used, the semipermeable membrane solution penetrates into the semipermeable membrane support, and a large amount of semipermeable membrane solution is required to obtain the desired semipermeable membrane thickness. There was a problem of becoming.

  In addition, in order to solve the problem that when the semipermeable membrane solution is applied, the semipermeable membrane support is curved in the width direction, a non-uniform semipermeable membrane is produced. A semipermeable membrane support in which the tensile strength ratio in the direction is 2: 1 to 1: 1 and the fiber orientation is dispersed has been proposed (see, for example, Patent Document 3). Further, Patent Document 3 proposes a method for adjusting the air permeability and pore size of the semipermeable membrane support for the purpose of improving the adhesion between the semipermeable membrane and the semipermeable membrane support and preventing the back-through. . However, the air permeability according to JIS L1096 is calculated on the basis of the amount of air passing from one side of the semipermeable membrane support through the inside of the semipermeable membrane support to another side, This does not accurately reflect the penetration of the semipermeable membrane solution applied on the surface to the non-coated surface. Therefore, when a semipermeable membrane solution is applied to a semipermeable membrane support having an air permeability in the range shown in Patent Document 3, the semipermeable membrane solution may fall through.

  Further, in Patent Document 4, when the semipermeable membrane solution is applied to a defective portion that exists locally as a spot on a wet nonwoven fabric sheet that is a semipermeable membrane support, the permeability of the semipermeable membrane solution is partially changed. In order to solve the problem that the thickness of the semipermeable membrane in this part may become extremely thin or the surface of the semipermeable membrane may be wrinkled due to being difficult to permeate, the composition constituting the wet nonwoven fabric There is a method of optimizing the number of times of hot-pressure processing of wet nonwoven fabric, the temperature, and the type of roll for the purpose of making it difficult for low density defects, which are places where the sheet density is low, in a sparse fiber state. Proposed. And in patent document 4, there is no low density fault, it is uniform, the adhesiveness of a semipermeable membrane and a semipermeable membrane support body is good, and a semipermeable membrane solution permeates a wet nonwoven fabric too much, and a semipermeable membrane becomes non-uniform | heterogenous. As a semipermeable membrane support capable of preventing this, a semipermeable membrane support with adjusted sheet density and pressure loss has been proposed. However, even in the case of a semipermeable membrane support having a sheet density and pressure loss in the range shown in Patent Document 4, there has been a case where the back-through occurs.

JP 2008-238147 A Japanese Patent Publication No. 4-21526 JP 2002-95937 A International Publication No. 2012/090874 Pamphlet

  An object of the present invention is to provide a semipermeable membrane support that is excellent in adhesiveness between a semipermeable membrane and a semipermeable membrane support and from which a semipermeable membrane solution does not penetrate, and a method for producing the same.

  The above problems have been solved by the following means.

(1) A semipermeable membrane support comprising a non-woven fabric comprising at least a main synthetic fiber and a binder synthetic fiber, wherein a melt of the binder synthetic fiber is present on at least one surface of the semipermeable membrane support. A semipermeable membrane support.
(2) The semipermeable membrane support according to the above (1), wherein the number of melting defects observed in an electron micrograph on the surface of the semipermeable membrane support is 2 or more per 1.0 mm ² .
(3) The semipermeable membrane supporting material according to the above (1) or (2), wherein the shape of the molten lees of the binder synthetic fiber is a branched shape.
(4) The semipermeable membrane support according to any one of (1) to (3), wherein the shape of the melted cocoon of the binder synthetic fiber is such that the tip diameter of the molten cocoon is smaller than the diameter of the main synthetic fiber.
(5) The molten soot shape of the molten binder of the binder synthetic fiber is at least one kind of void selected from the void between the main synthetic fibers, the void between the main synthetic fiber and the binder synthetic fiber, and the void between the binder synthetic fibers. The semipermeable membrane support according to any one of the above (1) to (4), which has a crossing shape.
(6) The above-mentioned (1) to (1) in which the molten cocoon of the binder synthetic fiber exists on the coating surface, which is the surface on which the semipermeable membrane of the semipermeable membrane support is coated, The semipermeable membrane support according to any one of 5).
(7) The semipermeable membrane support according to any one of the above (1) to (6), wherein the molten soot of the binder synthetic fiber is present on both surfaces of the semipermeable membrane support.
(8) A method for producing the semipermeable membrane support according to any one of (1) to (7), wherein a slurry containing at least a main synthetic fiber and a binder synthetic fiber is made by a wet papermaking method. Including a step of producing a wet paper and a step of hot pressing the wet paper obtained in the previous step with a hot roll, and confirming the surface temperature of the semipermeable membrane support immediately after the hot press processing. A process for producing a semipermeable membrane support, which is performed while
(9) The surface temperature of the semipermeable membrane support measured at a position less than 10 cm immediately after the nip after hot pressing is within the range of −65 ° C. to −20 ° C. with respect to the melting point of the binder synthetic fiber. The method for producing a semipermeable membrane supporting material according to (8), wherein the surface temperature of the hot roll in hot pressing is set.

In the semipermeable membrane supporting material of the present invention, molten soot of the binder synthetic fiber exists on at least one surface. The semipermeable membrane is less likely to peel from the semipermeable membrane support due to the anchor effect between the melted binder synthetic fiber present on the coated surface of the semipermeable membrane support and the semipermeable membrane, and the semipermeable membrane and semipermeable membrane support The effect that the adhesiveness with a body becomes favorable can be achieved. In addition, the presence of molten soot can achieve the effect of preventing the semipermeable membrane solution from getting through.
According to the method for producing a semipermeable membrane support of the present invention, the semipermeable membrane support of the present invention capable of achieving the above-described effects can be efficiently produced.

It is an electron micrograph of the semipermeable membrane supporting body surface before generating the melt flaw of a binder synthetic fiber. It is an electron micrograph of the surface of a semipermeable membrane support in which molten soot of a binder synthetic fiber exists. It is an electron micrograph of the semipermeable membrane supporting body surface which shows an example of the shape of the molten metal of a binder synthetic fiber. It is an electron micrograph of the semipermeable membrane supporting body surface which shows an example of the shape of the molten metal of a binder synthetic fiber. It is an electron micrograph of the semipermeable membrane supporting body surface which shows an example of the shape of the molten metal of a binder synthetic fiber. It is an electron micrograph of the semipermeable membrane supporting body surface which shows an example of the shape of the molten metal of a binder synthetic fiber. It is an electron micrograph of the cross section of a semipermeable membrane support which exists in the state where the molten iron of the binder synthetic fiber is lying. 2 is an electron micrograph of a cross section of a semipermeable membrane support that is present in a state where a melted flaw of a binder synthetic fiber is standing.

  The semipermeable membrane support of the present invention is a semipermeable membrane support made of a nonwoven fabric containing at least main synthetic fibers and binder synthetic fibers, and the binder synthetic fibers are formed on at least one surface of the semipermeable membrane support. It is characterized by the presence of molten soot.

  The semipermeable membrane support of the present invention is produced by forming a sheet by a wet papermaking method and then hot-pressing the sheet with a hot roll. At the time of hot pressing with a hot roll, the binder synthetic fiber melted by coming into contact with the hot roll becomes a short cocoon when leaving the hot roll, thereby forming a molten cocoon. FIG. 2 of Patent Document 3 (Japanese Patent Application Laid-Open No. 2002-95937) is a micrograph (200 times) of a semipermeable membrane support, but the binder synthetic fiber is melted and deformed, It cannot be confirmed. Further, the molten iron is not a portion where the binder synthetic fiber is melted and deformed into a film shape. For example, in the electron micrograph (35 times) of the semipermeable membrane support shown in FIG. 2 of Patent Document 4 (International Publication No. 2012/090874 pamphlet), the white part is the binder synthetic fiber. The binder synthetic fiber spreads in a film shape so as to close the gap between the main synthetic fibers, and does not have a hook shape.

As a method for measuring the number of molten irons, electron micrographs of both surfaces of the semipermeable membrane support are taken, and the number of molten irons per fixed area (1.0 mm ² ) is measured. When the width of the semipermeable membrane support is 10 × N cm, N points are measured. However, N is a positive integer. For example, when the width of the semipermeable membrane support is 30 cm, a total of three points are measured from the end in the width direction: a 5 cm spot, a 15 cm spot, and a 25 cm spot. In the case of a width of 100 cm, a total of 10 points including a point of 5 cm, a point of 15 cm, and a point of 95 cm are measured. At that time, the number of melted knots thinner than the diameter of the binder synthetic fiber before melting is measured. In order to discriminate molten metal, the magnification at the time of taking an electron micrograph is preferably 100 times or more, more preferably 200 times or more.

The number of molten iron is preferably 2 or more per 1.0 mm ² , more preferably 3 or more, and still more preferably 4 or more. Moreover, the number of molten iron is preferably 1000 or less per 1.0 mm ² . When there is no molten iron or when the number of molten iron is less than two, the effect of covering the depression between the main synthetic fibers is small, and the adhesion between the semipermeable membrane and the semipermeable membrane support is improved. It may not be seen. In addition, there is a risk that the semipermeable membrane solution may be broken through. There is no problem even if the number of molten iron exceeds 1000, but the effect is not different from the case of 1000 or less.

  The molten cocoon in the present invention is a part of the binder synthetic fiber that is greatly changed from the fiber shape before melting into a cocoon shape. The diameter of the molten soot is smaller than the diameter of the binder synthetic fiber before melting. In addition, the molten soot may adhere without being detached from the binder synthetic fiber, but may be detached from the binder synthetic fiber and independent. In addition, the shape of the molten iron is branched into fibrils and branched, stretched and thinned, both ends connected to the main synthetic fiber and binder synthetic fiber, and bent There are shapes. And the length and thickness of the molten iron are indefinite.

  In the present invention, the semipermeable membrane is less likely to be peeled off from the semipermeable membrane support due to the anchor effect between the molten cocoon of the binder synthetic fiber present on the coating surface of the semipermeable membrane support and the semipermeable membrane, The effect that adhesiveness with a semipermeable membrane support body improves can be achieved. When the semipermeable membrane solution is applied, most of the semipermeable membrane solution remains on the surface of the semipermeable membrane support, but a part of the semipermeable membrane solution enters a recess that is a space between fibers constituting the semipermeable membrane support. Go on. Thereafter, when the film is formed, it is presumed that the semipermeable membrane that has entered the recess cannot be easily removed due to the presence of the molten iron, and the adhesion between the semipermeable membrane and the semipermeable membrane support is increased.

  In addition, the presence of the molten soot in the depressions that are the gaps between the fibers constituting the semipermeable membrane support allows the molten soot to subdivide the gaps, thereby achieving the effect of suppressing the back-through of the semipermeable membrane solution. . The molten soot present on the coated surface also has the effect of suppressing the reverse penetration of the semipermeable membrane solution, but the molten soot present on the non-coated surface can more effectively suppress the strikethrough.

  In the present invention, it suffices that the molten fiber of the binder synthetic fiber is present on at least one surface of the semipermeable membrane support. However, the presence of both sides makes it possible to provide adhesion between the semipermeable membrane and the semipermeable membrane support. The effect of becoming better and the effect of preventing the back penetration of the semipermeable membrane solution are further enhanced.

  The shape of the molten iron is a shape in which the molten iron is branched and branched into a fibril shape, the shape of the tip of the molten iron is smaller than the diameter of the main synthetic fiber, or the gap between the main synthetic fibers, the main In the case where the molten metal is traversing at least one kind of gap selected from the gap between the synthetic fiber and the binder synthetic fiber and the gap between the binder synthetic fibers, the gap is subdivided without impairing the liquid permeability. Thus, the adhesion between the semipermeable membrane and the semipermeable membrane support and the effect of suppressing the back-through can be further enhanced.

  A semipermeable membrane support comprising fibrillated lyocell fiber, acrylic fiber, aramid fiber or the like as a fibrillated fiber is also known. However, since these fibrillated fibers do not have self-adhesive properties, they may fall off when they are not in contact with the binder synthetic fiber, which may cause a defect of the semipermeable membrane. On the other hand, in the present invention, in the shape in which the molten soot branches and branches into a fibril shape, since the molten soot itself is a binder synthetic fiber, it has self-adhesive properties, so there is a risk of dropping off. No.

  FIG. 1 is an electron micrograph of the surface of a semipermeable membrane support before generating molten soot of a binder synthetic fiber. Only a main synthetic fiber and a binder synthetic fiber in which no molten soot is present are present. The magnification of the electron micrograph is 100 times, and the scale bar indicates 100 μm.

  FIG. 2 is an electron micrograph of the surface of the semipermeable membrane support on which the molten melt of the binder synthetic fiber exists. The magnification of the electron micrograph is 100 times, and the scale bar is 100 μm. The molten iron exists so as to cover the depression that is a space between the main synthetic fibers arranged at random. The molten soot is generated from the binder synthetic fiber, and is firmly bonded to the main synthetic fiber and does not fall off.

  FIG. 3 is an electron micrograph of the surface of the semipermeable membrane support showing an example of the shape of the molten metal of the binder synthetic fiber. The magnification of the electron micrograph is 200 times, and the scale bar is 100 μm. The shape of the molten iron present in the portion surrounded by ○ is a shape that is branched into fibrils.

  FIG. 4 is an electron micrograph of the surface of the semipermeable membrane support showing an example of the shape of the melted binder synthetic fiber. The magnification of the electron micrograph is 200 times, and the scale bar is 100 μm. The shape of the molten iron present in the portion surrounded by ○ is a shape in which the tip diameter of the molten iron is smaller than the diameter of the main synthetic fiber. The tip diameter of the molten soot is the diameter of the tip of the molten soot generated starting from the branch point from the binder synthetic fiber when the molten soot adheres without leaving the binder synthetic fiber. Moreover, when it has detached | separated from the binder synthetic fiber, it is the diameter of the both ends of a molten iron. The diameter of the tip of the molten iron is the width of the tip of the molten iron calculated based on the length of the scale bar in the electron micrograph.

  FIG. 5 is an electron micrograph of the surface of the semipermeable membrane support showing an example of the shape of the molten metal of the binder synthetic fiber. The magnification of the electron micrograph is 200 times, and the scale bar is 100 μm. The molten soot present in the portion surrounded by ○ crosses at least one kind of void selected from the void between the main synthetic fibers, the void between the main synthetic fibers and the binder synthetic fibers, and the void between the binder synthetic fibers. ing. Moreover, the tip diameter of the molten iron is thinner than the diameter of the main synthetic fiber.

  FIG. 6 is an electron micrograph of the surface of the semipermeable membrane support showing an example of the shape of the molten metal of the binder synthetic fiber. The magnification of the electron micrograph is 100 times, and the scale bar is 100 μm. The molten soot present in the portion surrounded by ○ crosses at least one kind of void selected from the void between the main synthetic fibers, the void between the main synthetic fibers and the binder synthetic fibers, and the void between the binder synthetic fibers. ing. However, since the tip diameter of the molten iron is larger than the diameter of the main synthetic fiber, the effect of subdividing the voids is small compared to the molten iron present in the portion surrounded by the circle in FIG.

  When molten soot is present on the coated surface, it is preferable that the molten soot is in a lying state. Because the molten soot is in a lying state, it becomes possible to randomly arrange the molten soot in the gaps between the fibers constituting the semipermeable membrane support, and efficiently subdivide the large gaps between the fibers. It is possible to enhance the adhesion between the semipermeable membrane and the semipermeable membrane support and the effect of suppressing the see-through of the semipermeable membrane solution. In addition, when the molten iron stands in the vertical direction or the oblique direction with respect to the surface of the semipermeable membrane support, the molten iron is stuck in the semipermeable membrane in the vicinity of the semipermeable membrane support. The semi-permeable membrane performance may be improved in the state where the molten iron is laid down than in the state where it stands in the vertical direction or the oblique direction.

  FIG. 7 is an electron micrograph of a cross section of the semipermeable membrane support in which a molten soot of the binder synthetic fiber exists. The magnification of the electron micrograph is 200 times, and the scale bar is 100 μm. Molten soot has been generated, but the molten soot is in a sleeping state, and standing molten iron cannot be confirmed.

  FIG. 8 is an electron micrograph of a cross section of the semipermeable membrane support in which molten binder of the binder synthetic fiber exists. The magnification of the electron micrograph is 200 times, and the scale bar is 100 μm. It can be confirmed that the molten iron present in the two portions surrounded by ○ is present in a standing state.

  As a method for laying the molten cake, after generating molten cake, hot pressing with heated hot rolls, hot pressing with heated and unheated rolls, pressurizing with unheated rolls Examples thereof include a method of performing processing and the like, and a method of holding a surface on which molten flaws are generated so as to contact a hot roll. These methods can be performed alone or in combination.

  In the present invention, the main synthetic fiber is a fiber that forms the skeleton of the semipermeable membrane support. Examples of the main synthetic fibers include polyolefin fibers, polyamide fibers, polyacrylic resins, vinylon resins, vinylidene resins, polyvinyl chloride resins, polyester resins, benzoate resins, polyclar resins, phenol fibers, and the like. Polyester fibers having a high viscosity are more preferable. Semi-synthetic fibers such as acetate, triacetate, promix, and regenerated fibers such as rayon, cupra, and lyocell fiber may be contained within a range that does not impair the performance.

  The diameter of the main synthetic fiber is not particularly limited, but is preferably 30 μm or less. More preferably, it is 2-20 micrometers, More preferably, it is 4-20 micrometers, Especially preferably, it is 6-20 micrometers. When the thickness is less than 2 μm, the semipermeable membrane solution hardly penetrates into the semipermeable membrane support, and the adhesion between the semipermeable membrane and the semipermeable membrane support may be deteriorated. If the diameter of the main synthetic fiber exceeds 30 μm, in order to obtain a desired semipermeable membrane thickness, there is a problem that a large amount of semipermeable membrane solution is required, or there is a case where the semipermeable membrane solution is broken through. May occur. Moreover, the main synthetic fibers on the surface of the nonwoven fabric are likely to stand, and the performance of the semipermeable membrane may be reduced by penetrating the semipermeable membrane.

  The fiber length of the main synthetic fiber is not particularly limited, but is preferably 1 to 12 mm, more preferably 3 to 10 mm, and further preferably 4 to 6 mm. The cross-sectional shape of the main synthetic fiber is preferably circular, and the cross-sectional aspect ratio (fiber cross-section major axis / fiber cross-section minor axis) of the fiber before dispersion in water in the paper making process is preferably less than 1.0 to 1.2. . When the fiber cross-sectional aspect ratio is 1.2 or more, the fiber dispersibility may decrease, or the occurrence of entanglement or entanglement may adversely affect the uniformity of the semipermeable membrane support and the smoothness of the coated surface. is there. However, fibers having irregular cross-sections such as T-type, Y-type, and triangle can also be contained within a range that does not hinder other properties such as fiber dispersibility for preventing back-through and surface smoothness.

  The aspect ratio (fiber length / diameter) of the main synthetic fiber is preferably 200 to 1000, more preferably 220 to 900, and still more preferably 280 to 800. When the aspect ratio is less than 200, the dispersibility of the fiber is good, but the fiber may fall off the paper making wire during paper making, or the fiber may be stuck in the paper making wire and the peelability from the wire may deteriorate. is there. On the other hand, if it exceeds 1000, although it contributes to the formation of a three-dimensional network of fibers, the occurrence of entanglement and entanglement may adversely affect the uniformity of the semipermeable membrane support and the smoothness of the coated surface. .

  In the nonwoven fabric constituting the semipermeable membrane support of the present invention, the content of the main synthetic fiber is preferably 40 to 90% by mass, more preferably 50 to 80% by mass, and still more preferably 60 to 70% by mass. When the content of the main synthetic fiber is less than 40% by mass, the liquid permeability may be lowered. Moreover, when it exceeds 90 mass%, there exists a possibility that it may be broken by insufficient strength.

  The semipermeable membrane support of the present invention contains a binder synthetic fiber. By incorporating the process of softening or melting the binder synthetic fiber into the production process of the semipermeable membrane support, the binder synthetic fiber improves the mechanical strength of the semipermeable membrane support. For example, a semipermeable membrane support can be produced by a wet papermaking method, and the binder synthetic fiber can be softened or melted in a subsequent drying step.

  Examples of the binder synthetic fiber include core-sheath fibers (core-shell type), parallel fibers (side-by-side type), composite fibers such as radially divided fibers, unstretched fibers, and the like. Since the composite fiber hardly forms a film, the mechanical strength can be improved while maintaining the space of the semipermeable membrane support. More specifically, a combination of polypropylene (core) and polyethylene (sheath), a combination of polypropylene (core) and ethylene vinyl alcohol (sheath), a combination of high melting point polyester (core) and low melting point polyester (sheath), polyester, etc. Of undrawn fiber. In addition, a single fiber (fully fused type) composed only of a low melting point resin such as polyethylene or polypropylene, or a hot water-soluble binder such as polyvinyl alcohol easily forms a film in the drying process of the semipermeable membrane support. However, it can be used as long as the properties are not impaired. In the present invention, a combination of a high-melting point polyester (core) and a low-melting point polyester (sheath) and unstretched polyester fibers can be preferably used.

  Although the diameter of a binder synthetic fiber is not specifically limited, Preferably it is 2-20 micrometers, More preferably, it is 5-15 micrometers, More preferably, it is 7-12 micrometers. Moreover, it is preferable that it is a diameter different from a main synthetic fiber, and it is especially preferable that it is a diameter thinner than a main synthetic fiber. Since the diameter of the synthetic fiber is different from that of the main synthetic fiber, the binder synthetic fiber plays a role of forming a uniform three-dimensional network together with the main synthetic fiber in addition to improving the mechanical strength of the semipermeable membrane support. Furthermore, in the step of raising the temperature to the softening temperature or melting temperature of the binder synthetic fiber, the smoothness of the semipermeable membrane support surface can be improved, and in this step, it is more effective when accompanied by pressurization. is there. In the present invention, the number of melted slag thinner than the diameter of the binder synthetic fiber before melting is measured. When the diameter of the binder synthetic fiber, which is a preferred embodiment, is smaller than the diameter of the main synthetic fiber, the melted rice cake that is thinner than the diameter of the binder synthetic fiber before melting is thinner than the diameter of the main synthetic fiber, It can be determined that the melt is thinner than the diameter of the main synthetic fiber.

  Although the fiber length of a binder synthetic fiber is not specifically limited, Preferably it is 1-12 mm, More preferably, it is 3-10 mm, More preferably, it is 4-6 mm. The cross-sectional shape of the binder synthetic fiber is preferably circular, but fibers having irregular cross-sections such as T-type, Y-type, and triangular are also within the range that does not hinder other properties for preventing back-through and smoothness of the coated surface. Can be contained.

  The aspect ratio (fiber length / diameter) of the binder synthetic fiber is preferably 200 to 1000, more preferably 300 to 800, and still more preferably 400 to 700. When the aspect ratio is less than 200, the dispersibility of the fiber is good, but the fiber may drop off from the papermaking wire during papermaking, or the fiber may pierce the papermaking wire and the peelability from the wire may deteriorate. is there. On the other hand, if it exceeds 1000, the binder synthetic fiber contributes to the formation of a three-dimensional network, but the fiber may be entangled or the tangle may adversely affect the uniformity of the nonwoven fabric and the smoothness of the coated surface. .

  In the nonwoven fabric constituting the semipermeable membrane support of the present invention, the content of the binder synthetic fiber is preferably 10 to 60% by mass, more preferably 20 to 50% by mass, and still more preferably 25 to 40% by mass. In the above-mentioned range, the molten soot can be increased by increasing the content of the binder synthetic fiber. When the content of the binder synthetic fiber is less than 10% by mass, it may be broken due to insufficient strength, and molten flaws may not occur. Moreover, when it exceeds 60 mass%, there exists a possibility that liquid permeability may fall.

  A shape in which the shape of the molten iron is branched, a shape in which the tip diameter of the molten iron is thinner than the diameter of the main synthetic fiber, or a gap between the main synthetic fibers, a gap between the main synthetic fiber and the binder synthetic fiber, and binder synthesis In order for the molten iron to cross at least one kind of gap selected from the gaps between the fibers, the main synthetic fibers and the binder synthetic fibers constituting the nonwoven fabric may be arranged in random directions. It is necessary and the binder synthetic fiber must be present at the part in contact with the heat roll. In order to arrange them randomly, the ratio of the diameter of the main synthetic fiber to the diameter of the binder synthetic fiber (the diameter of the main synthetic fiber / the diameter of the binder synthetic fiber) is 0.2 to 4.0 / 1.0. Preferably, it is 0.3 to 3.0 / 1.0, more preferably 0.4 to 2.5 / 1.0. When the diameter of the main synthetic fiber / the diameter of the binder synthetic fiber is less than 0.2 / 1.0, the number of the main synthetic fibers is insufficient because the diameter of the binder synthetic fiber is large. Thus, the binder synthetic fiber may not be randomly arranged. On the other hand, when the diameter of the main synthetic fiber / the diameter of the binder synthetic fiber exceeds 4.0 / 1.0, the binder synthetic fiber is buried between the main synthetic fibers and is present in the portion in contact with the heat roll. May be insufficient.

  The method for producing the semipermeable membrane support of the present invention will be described. In the semipermeable membrane supporting material of the present invention, after a sheet is produced by a wet papermaking method, the sheet is hot-pressed by a hot roll.

  In the wet papermaking method, first, at least the main synthetic fiber and the binder synthetic fiber are uniformly dispersed in water, and then the final fiber concentration is 0.01 to 0. Slurries prepared to 50% by weight are made up with a paper machine to obtain wet paper. In order to make the dispersibility of the fibers uniform, chemicals such as dispersants, antifoaming agents, hydrophilic agents, antistatic agents, polymer thickeners, mold release agents, antibacterial agents, bactericides, etc. may be added during the process. is there.

  As the papermaking method, for example, a papermaking method such as a long mesh, a circular mesh, or an inclined wire method can be used. Use a paper machine with at least one paper machine selected from the group of these paper machines, or a combination machine with two or more same or different paper machines selected online from these paper machine groups can do. In addition, when manufacturing a nonwoven fabric having a multilayer structure of two or more layers, a wet paper made by each paper machine is laminated, or one sheet is formed and then formed on the sheet. A method of casting a slurry in which fibers are dispersed can be used.

  Sheets are obtained by drying wet paper produced by a paper machine with a Yankee dryer, air dryer, cylinder dryer, suction drum dryer, infrared dryer, or the like. When the wet paper is dried, it is brought into close contact with a hot roll such as a Yankee dryer and dried by heat and pressure to improve the smoothness of the contacted surface. Hot-pressure drying means that the wet paper is pressed against the heat roll with a touch roll or the like and dried. The surface temperature of the hot roll is preferably 100 to 180 ° C, more preferably 100 to 160 ° C, and still more preferably 110 to 160 ° C. The pressure is preferably 50 to 1000 N / cm, more preferably 100 to 800 N / cm.

  Next, although hot press processing by a hot roll is demonstrated, the manufacturing method of the semipermeable membrane support body of this invention is not limited to the following description. In a hot-pressure processing apparatus (calendar apparatus), a sheet is hot-pressed by passing the sheet between nip rolls. Examples of the combination of rolls include two metal rolls, a metal roll and a resin roll, and a metal roll and a cotton roll. At least one of the two rolls is heated and used as a hot roll. Mainly metal rolls are used as heat rolls. It is also possible to perform the hot pressing with a hot roll two or more times. In that case, two or more sets of rolls arranged in series may be used, or one set of rolls may be used. You may process twice. If necessary, the front and back of the sheet may be reversed. A desired semipermeable membrane support can be obtained by controlling the surface temperature of the hot roll, the nip pressure between the rolls, and the processing speed of the sheet.

  In order to generate molten flaws, it is important to attach a sheet to the hot roll during hot pressing with the hot roll. For this purpose, it is important to increase the hot roll temperature to near the melting point of the binder synthetic fiber and to increase the nip pressure. Moreover, the length of the molten iron can be adjusted to some extent by controlling the processing speed. In addition, the molten soot can be increased by increasing the content of the binder synthetic fiber.

  As an indicator of the occurrence of molten soot, it is necessary not to control the surface temperature of the hot roll but to confirm the heat actually transmitted to the semipermeable membrane support. For this purpose, it is important to confirm the surface temperature of the semipermeable membrane support immediately after the hot pressing with a hot roll. In order to generate molten soot, the surface temperature of the semipermeable membrane support measured at a position less than 10 cm from immediately after the nip after the semipermeable membrane support was hot-pressed by a hot roll was determined as follows. It is preferable to be within a range of −65 ° C. to −20 ° C. with respect to the melting point. More preferably, it exists in the range of -60 degreeC--25 degreeC, More preferably, it is the range of -55 degreeC--25 degreeC. By measuring the surface temperature of the semipermeable membrane support at a position less than 10 cm immediately after the nip, the surface temperature of the semipermeable membrane support at the nip can be estimated. Experience has shown that the surface temperature of the semipermeable membrane support measured at a position less than 10 cm immediately after the nip is 1-5 ° C. lower than the surface temperature at the nip. It is preferable to set the conditions for hot pressing so as to be in the above temperature range.

  For example, when the melting point of the binder synthetic fiber is 260 ° C, the surface temperature of the semipermeable membrane support is preferably 195 to 240 ° C, more preferably 200 to 235 ° C. It is necessary to set the surface temperature of the hot roll so as to match the surface temperature of the semipermeable membrane support. For example, when the surface temperature of the semipermeable membrane support is 220 ° C. measured at a position 9 cm from immediately after the nip after the semipermeable membrane support is hot-pressed with a hot roll, the hot roll surface temperature is 221 ° C. to Set to 225 ° C.

  The nip pressure of the roll in the hot pressing is preferably 250 to 1700 N / cm, more preferably 450 to 1400 N / cm. In order to generate molten soot, it is important to attach a sheet to the hot roll during hot pressing with the hot roll, and to that end, it is important to increase the nip pressure. When the nip pressure is less than 250 N / cm, molten flaws may not occur due to poor adhesion between the hot roll and the sheet. On the other hand, when it exceeds 1700 N / cm, compared with the case of 1700 N / cm, the effect of increasing melt flaws is not changed, and the roll life may be shortened by increasing the excessive load on the roll.

  The processing speed in the hot pressing is preferably 4 to 100 m / min, more preferably 10 to 80 m / min. By adjusting the processing speed in the hot pressing, the length of the molten iron can be adjusted to some extent. The length of the molten iron is the length from the branch point from the binder synthetic fiber to the tip of the molten iron when the molten iron adheres without leaving the binder synthetic fiber. Further, when the molten iron is separated from the binder synthetic fiber, the length is from the tip of the molten iron to the opposite tip. By reducing the processing speed, the molten iron can be lengthened. For example, when the processing speed is 10 m / min, the length of the molten iron is often 50 to 400 μm, and when the processing speed is 40 m / min, the length of the molten iron is often 10 to 150 μm.

  Also, in order to attach the sheet after hot pressing with a hot roll to the hot roll, do not apply a chemical such as a mold release agent to the hot roll, It is important to keep it extremely low. When a large amount of the release agent is applied, even if the temperature of the hot roll and the nip pressure are increased, the sheet may not adhere to the hot roll, and molten flaws may not occur.

Although the basic weight of a semipermeable membrane support body is not specifically limited, 20-150 g / m < ² > is preferable, More preferably, it is 50-100 g / m < ² >. If it is less than 20 g / m ² , sufficient tensile strength may not be obtained. Moreover, when it exceeds 150 g / m < ² >, a liquid flow resistance may become high, thickness may increase, and a predetermined amount of semipermeable membrane may not be accommodated in a unit or a module.

The density of the semi-permeable membrane support is preferably 0.5 to 1.0 g / cm ^3, more preferably 0.6~0.9g / cm ^3. When the density of the semipermeable membrane support is less than 0.5 g / cm ³ , the thickness increases, and the area of the semipermeable membrane that can be incorporated into the unit is reduced. As a result, the life of the semipermeable membrane is shortened. May end up. On the other hand, when it exceeds 1.0 g / cm ³ , the liquid permeability may be lowered, and the life of the semipermeable membrane may be shortened.

  The thickness of the semipermeable membrane support is preferably 50 to 150 μm, more preferably 60 to 130 μm, and still more preferably 70 to 120 μm. When the thickness of the semipermeable membrane support exceeds 150 μm, the area of the semipermeable membrane that can be incorporated into the unit is reduced, and as a result, the life of the semipermeable membrane may be shortened. On the other hand, if it is less than 50 μm, sufficient tensile strength may not be obtained.

  The present invention will be described in more detail with reference to examples. Hereinafter, unless otherwise specified, the parts and ratios described in the examples are based on mass.

(Example 1-1)
Main synthetic fiber (stretched polyester fiber, diameter 12.5 μm, fiber length 5 mm), binder synthetic fiber (unstretched polyester fiber, diameter 10.5 μm, fiber length 5 mm, melting point 260 ° C.) at a blending ratio of 70:30 After mixing and dispersing in water and forming wet paper with a circular paper machine, it was hot-pressure dried with a Yankee dryer having a surface temperature of 130 ° C. to obtain a sheet having a basis weight of 80 g / m ² .

  The obtained sheet was hot-pressed under the conditions of a heated metal roll surface temperature of 215 ° C., a pressure of 1000 N / cm, and a processing speed of 30 m / min, using a calendar device that is a combination of a heated metal roll and a resin roll in the first stage. The surface of the sheet that is in contact with the heated metal roll is in contact with the resin roll using a calendar device that is a combination of the second stage resin roll and heated metal roll. / Cm and hot pressing under conditions of a processing speed of 30 m / min, a semipermeable membrane support was obtained. In addition, the surface which contacted the heating metal roll first was made into the application surface.

(Example 1-2)
A semipermeable membrane support was obtained in the same manner as in Example 1-1 except that the temperatures of the heated metal roll of the first stage and the heated metal roll of the second stage were changed to 220 ° C. and 220 ° C., respectively. In addition, the surface which contacted the heating metal roll first was made into the application surface.

(Example 1-3)
A semipermeable membrane support was obtained in the same manner as in Example 1-1 except that the temperature of the heated metal roll of the first stage and the heated metal roll of the second stage were changed to 230 ° C. and 240 ° C., respectively. In addition, the surface which contacted the heating metal roll first was made into the application surface.

(Example 1-4)
A semipermeable membrane support was obtained in the same manner as in Example 1-1 except that the temperature of the heated metal roll of the first stage and the heated metal roll of the second stage were changed to 230 ° C. and 240 ° C., respectively. In addition, the surface which contacted the resin roll first was made into the application surface.

(Example 1-5)
A semipermeable membrane support was obtained in the same manner as in Example 1-1 except that the temperatures of the heated metal roll of the first stage and the heated metal roll of the second stage were changed to 225 ° C. and 213 ° C., respectively. In addition, the surface which contacted the heating metal roll first was made into the application surface.

(Example 1-6)
The blending ratio of the main synthetic fiber (stretched polyester fiber, diameter 12.5 μm, fiber length 5 mm) and binder synthetic fiber (unstretched polyester fiber, diameter 10.5 μm, fiber length 5 mm, melting point 260 ° C.) is 75:25. A semipermeable membrane support was obtained in the same manner as in Example 1-3 except that the change was made. In addition, the surface which contacted the heating metal roll first was made into the application surface.

(Example 1-7)
The blending ratio of the main synthetic fiber (stretched polyester fiber, diameter 12.5 μm, fiber length 5 mm) and binder synthetic fiber (unstretched polyester fiber, diameter 10.5 μm, fiber length 5 mm, melting point 260 ° C.) is 60:40 A semipermeable membrane support was obtained in the same manner as in Example 1-3 except that the change was made. In addition, the surface which contacted the heating metal roll first was made into the application surface.

(Comparative Example 1-1)
A semipermeable membrane support was obtained in the same manner as in Example 1-1 except that the temperature of the heated metal roll of the first stage and the heated metal roll of the second stage were changed to 205 ° C. and 205 ° C., respectively. In addition, the surface which contacted the heating metal roll first was made into the application surface.

  Table 1 shows binder synthetic fiber content (%), melting point of binder synthetic fiber (° C.), combination of rolls in hot pressing (first stage) and hot pressing (second stage), types of hot rolls, half The surface temperature (° C.), nip pressure (N / cm), and processing speed (m / min) of the permeable membrane support were shown.

  In the examples and comparative examples, the surface temperature of the semipermeable membrane support is the semipermeable membrane support measured at a position 9 cm immediately after the nip after the semipermeable membrane support was hot-pressed by a hot roll. It was the surface temperature of the body and was measured with a radiation thermometer AD-5611A with a laser manufactured by A & D. Moreover, in an Example and a comparative example, melting | fusing point is the temperature of the maximum point when it measures on 25 degreeC to 300 degreeC on the temperature rising conditions of 10 degree-C per minute using the differential scanning thermal analyzer DSC7 made from PERKIN ELMER. is there.

  For the semipermeable membrane supports obtained in the examples and comparative examples, the observation of the molten iron and the evaluation of the semipermeable membrane penetration, the semipermeable membrane adhesion and the semipermeable membrane surface observation were performed, and the results are shown in Table 2. Indicated.

(Observation of molten soot of binder synthetic fiber)
Electron micrographs on the coated and non-coated surfaces of the semipermeable membrane support were taken at a magnification of 200 times, and the number of molten iron per 1.0 mm ² was measured. In addition, the shape and state (standing / sleeping) of the observed molten iron were also observed. “Fibril”, “thin” and “cross” in Table 2 have the following meanings.

"Fibrils": A shape in which molten iron is branched into fibrils

“Thin”: The shape in which the tip diameter of the molten iron is smaller than the diameter of the main synthetic fiber

“Transverse”: A shape in which the molten iron crosses at least one kind of void selected from voids between the main synthetic fibers, voids between the main synthetic fibers and the binder synthetic fibers, and voids between the binder synthetic fibers.

(Semi-permeable membrane back)
Using a constant speed coating device (trade name: Automatic Film Applicator, manufactured by Yasuda Seiki Co., Ltd.) having a certain clearance, a semipermeable membrane support is set on the mount, and the coating surface of the semipermeable membrane support is black. A DMF solution (concentration: 19%) of a polysulfone resin mixed with an oil-based ink was applied, and after coating, the amount of the polysulfone resin that had penetrated the semipermeable membrane support and appeared on the mount was visually observed. The film was evaluated for breakthrough.

1: There is no showthrough. Very good level.
2: It is a small dot-like shape, and it is slightly behind. Good level.
3: It is a small dot-like shape and is seen through. Practically usable level.
4: It is a large dot-like shape, and there are many see-throughs. Unusable level for practical use.

(Semipermeable membrane adhesion)
Using a constant-speed coating device (trade name: TQC fully automatic film applicator, manufactured by Cortec Co., Ltd.) having a certain clearance, a DMF solution of polysulfone resin (concentration: 19%) is applied to the application surface of the semipermeable membrane support. The semipermeable membrane made of polysulfone resin was produced on the surface of the semipermeable membrane support by performing the work, washing with water and drying. The adhesion between the semipermeable membrane and the semipermeable membrane support was judged by the following method.

  The semipermeable membrane supporting material on which the semipermeable membrane is produced is cut into a sample having a width of 24 mm (cross direction with respect to the application direction) × length of 50 mm (application direction). A cellophane adhesive tape (manufactured by Nichiban Co., Ltd., trade name: Elpac (registered trademark) LP24) cut to a width of 24 mm and a length of 30 mm is pasted on the non-coated surface of the cut semipermeable membrane support, and only the 10 mm length portion is attached The width of 24 mm and the length of 20 mm are left as an adhesive part. Next, an adhesive part of an adhesive memo (manufactured by Lion Koki Co., Ltd., trade name: stick-on-note SN-23) is attached to a 24 mm wide × 10 mm long part of the coated surface. With the adhesive part of the cellophane adhesive tape (24 mm × 20 mm) and the non-adhesive part of the adhesive memo, depending on the state when applying force by pulling by hand in the direction where the semipermeable membrane and the semipermeable membrane support peel off, Semipermeable membrane adhesion was judged. Five samples were prepared and tested five times.

  When cellophane adhesive tape is applied to the coated and non-coated surfaces and both cellophane adhesive tapes are pulled, in most cases, separation occurs between the semipermeable membrane and the semipermeable membrane support, resulting in semipermeable membrane adhesion. It was difficult to evaluate sex. The adhesiveness between the semipermeable membrane and the semipermeable membrane support can be determined by using an adhesive memo having a lower adhesiveness than the cellophane adhesive tape and confirming where the peeling has occurred.

Criteria 1: Peeling occurred between the semipermeable membrane and the adhesive memo in all five tests. Very good level.
2: Peeling occurred between the semipermeable membrane and the adhesive memo in 3 to 4 tests. Good level.
3: In one or two tests, peeling occurred between the semipermeable membrane and the adhesive memo. Practically lower limit level.
4: In all five tests, delamination occurred between the semipermeable membrane and the semipermeable membrane support. Unusable level.

(Semi-permeable membrane surface observation)
Regarding the semipermeable membrane produced by the evaluation of the above (semipermeable membrane adhesiveness), the semipermeable membrane surface is randomly observed at five locations under the microscope, and the fibers and molten soot are formed near the semipermeable membrane surface and the semipermeable membrane surface. The presence or absence was confirmed.

  The semipermeable membrane supporting materials of Example 1-1 to Example 1-7 achieved practically usable levels in semipermeable membrane penetration, semipermeable membrane adhesion, and semipermeable membrane surface observation. In particular, the semipermeable membrane supports of Examples 1-3, 1-4, and 1-7, which had a large amount of molten wrinkles on the coated surface, had very good semipermeable membrane adhesion. In addition, in the semipermeable membrane supporting materials of Examples 1-3, 1-4, 1-6, and 1-7 in which there were many melt defects on the non-coated surface, no see-through occurred. The semipermeable membrane support of Example 1-6 in which the content of the binder synthetic fiber is 25% by mass is compared with the semipermeable membrane support of Examples 1-3 and 1-7. Although there were few numbers and the semipermeable membrane adhesiveness was a favorable level, there existed a place which is easy to peel partially.

  As a result of observing the shape of the molten iron, the shape of the molten iron in the semipermeable membrane supporting materials of Examples 1-1 to 1-7 was a shape in which the molten iron was branched and branched into a fibril, At least one kind of void selected from a shape in which the diameter of the tip is thinner than the main synthetic diameter, a void between the main synthetic fibers, a void between the main synthetic fibers and the binder synthetic fibers, and a void between the binder synthetic fibers is melted. There were many crossing shapes.

  When the surface of the semipermeable membrane was observed with a microscope, the semipermeable membrane support of Example 1-4, which had a lot of molten soot on the coated surface and was standing, did not penetrate the semipermeable membrane. In the vicinity of the semipermeable membrane surface, molten soot was observed. However, this was a level with no practical problem.

  The semipermeable membrane support of Example 1-5 has less molten soot on the non-coated surface, but since there were many molten soot on the coated surface, the penetration of the semipermeable membrane solution was suppressed by the molten soot on the coated surface, Although it was a small dot and a breakthrough occurred, it was a practically usable level.

  In contrast to the semipermeable membrane supports of Examples 1-1 to 1-7, the semipermeable membrane support of Comparative Example 1-1 has no molten soot on both the coated surface and the non-coated surface. Although it was a small dot and a breakthrough occurred, it was a practically usable level. However, the semipermeable membrane adhesiveness was poor and it was practically unusable. Further, when the surface of the semipermeable membrane was observed with a microscope, the main synthetic fibers penetrating the semipermeable membrane were found, which was a practically unusable level.

(Example 2-1)
Main synthetic fiber (stretched polyester fiber, diameter 17.5 μm, fiber length 5 mm), binder synthetic fiber (unstretched polyester fiber, diameter 10.5 μm, fiber length 5 mm, melting point 260 ° C.) at a blending ratio of 70:30 After mixing and dispersing in water and forming wet paper with a circular paper machine, it was hot-pressure dried with a Yankee dryer having a surface temperature of 130 ° C. to obtain a sheet having a basis weight of 80 g / m ² .

  The obtained sheet was hot-pressed under the conditions of a heated metal roll surface temperature of 225 ° C., a pressure of 1000 N / cm, and a processing speed of 30 m / min, using a calendar device that is a combination of a heated metal roll and a resin roll in the first stage. The surface temperature of the heated metal roll is 225 ° C. and the pressure is 1000 N, using a calendar device that is a combination of the second stage resin roll and the heated metal roll so that the surface of the sheet continuously contacting the heated metal roll is in contact with the resin roll. / Cm and hot pressing under conditions of a processing speed of 30 m / min, a semipermeable membrane support was obtained. In addition, the surface which contacted the heating metal roll first was made into the application surface.

(Example 2-2)
A semipermeable membrane support was obtained in the same manner as in Example 2-1, except that the temperatures of the heated metal roll of the first stage and the heated metal roll of the second stage were changed to 230 ° C. and 230 ° C., respectively. In addition, the surface which contacted the heating metal roll first was made into the application surface.

(Example 2-3)
A semipermeable membrane support was obtained in the same manner as in Example 2-1, except that the temperatures of the heated metal roll of the first stage and the heated metal roll of the second stage were changed to 235 ° C. and 240 ° C., respectively. In addition, the surface which contacted the heating metal roll first was made into the application surface.

(Example 2-4)
A semipermeable membrane support was obtained in the same manner as in Example 2-1, except that the temperatures of the heated metal roll of the first stage and the heated metal roll of the second stage were changed to 235 ° C. and 240 ° C., respectively. In addition, the surface which contacted the resin roll first was made into the application surface.

(Example 2-5)
A semipermeable membrane support was obtained in the same manner as in Example 2-1, except that the temperature of the heated metal roll of the first stage and the heated metal roll of the second stage were changed to 230 ° C. and 220 ° C., respectively. In addition, the surface which contacted the heating metal roll first was made into the application surface.

(Comparative Example 2-1)
A semipermeable membrane support was obtained in the same manner as in Example 2-1, except that the temperature of the heated metal roll of the first stage and the heated metal roll of the second stage were changed to 210 ° C and 210 ° C, respectively. In addition, the surface which contacted the heating metal roll first was made into the application surface.

  Table 3 shows binder synthetic fiber content (%), melting point of binder synthetic fiber (° C.), combination of rolls in hot pressing (first stage) and hot pressing (second stage), kind of hot roll, half The surface temperature (° C.), nip pressure (N / cm), and processing speed (m / min) of the permeable membrane support were shown.

  For the semipermeable membrane supports obtained in the examples and comparative examples, the observation of the molten iron and the evaluation of the semipermeable membrane penetration, the semipermeable membrane adhesiveness and the semipermeable membrane surface observation were performed, and the results are shown in Table 4. Indicated.

  The semipermeable membrane supports of Examples 2-1 to 2-5 achieved practically usable levels in the semipermeable membrane penetration, semipermeable membrane adhesion, and semipermeable membrane surface observation. In particular, the semipermeable membrane supports of Examples 2-2 to 2-5, which had a large amount of molten wrinkles on the coated surface, had very good semipermeable membrane adhesion. In addition, the semipermeable membrane supports of Examples 2-1 to 2-4, which had many melt defects on the non-coated surface, had a good evaluation of the semipermeable membrane penetration.

  When the surface of the semipermeable membrane was observed with a microscope, the semipermeable membrane support of Example 2-4, which had a lot of molten soot on the coated surface and was standing, did not penetrate the semipermeable membrane. In the vicinity of the semipermeable membrane surface, molten soot was observed. However, this was a level with no practical problem.

  Although the semipermeable membrane support of Example 2-5 has a small amount of molten wrinkles on the non-coated surface, since there were many molten wrinkles on the coated surface, the penetration of the semipermeable membrane solution was suppressed by the molten wrinkles on the coated surface, Although it was a small dot and a breakthrough occurred, it was a practically usable level.

  As a result of observing the shape of the molten iron, the shape of the molten iron in the semipermeable membrane supporting materials of Examples 2-1 to 2-5 is a shape in which the molten iron is branched and branched into a fibril, At least one kind of void selected from a shape in which the diameter of the tip is thinner than the main synthetic diameter, a void between the main synthetic fibers, a void between the main synthetic fibers and the binder synthetic fibers, and a void between the binder synthetic fibers is melted. There were many crossing shapes.

  In contrast to the semipermeable membrane supports of Examples 2-1 to 2-5, the semipermeable membrane support of Comparative Example 2-1 has no molten soot on both the coated surface and the non-coated surface. Although it was a small dot and a breakthrough occurred, it was a practically usable level. However, the semipermeable membrane adhesiveness was poor and it was practically unusable. Further, when the surface of the semipermeable membrane was observed with a microscope, the main synthetic fibers penetrating the semipermeable membrane were found, which was a practically unusable level.

(Example 3-1)
Main synthetic fiber 1 (stretched polyester fiber, diameter 12.5 μm, fiber length 5 mm), main synthetic fiber 2 (stretched polyester fiber, diameter 7.5 μm, fiber length 5 mm) Binder synthetic fiber (unstretched polyester fiber, diameter) 10.5 μm, fiber length 5 mm, melting point 260 ° C.) is mixed and dispersed in water at a mixing ratio of 35:35:30, wet paper is formed with a circular net paper machine, and then heated with a Yankee dryer having a surface temperature of 130 ° C. Pressure drying was performed to obtain a sheet having a basis weight of 80 g / m ² .

  The obtained sheet was hot-pressed under the conditions of a heated metal roll surface temperature of 230 ° C., a pressure of 1000 N / cm, and a processing speed of 30 m / min, using a calendar device that is a combination of a heated metal roll and a resin roll in the first stage. The surface of the sheet in contact with the heated metal roll is in contact with the resin roll, using a calendar device of a combination of the second stage resin roll and heated metal roll, the surface temperature of the heated metal roll is 230 ° C., and the pressure is 1000 N. / Cm and hot pressing under conditions of a processing speed of 30 m / min, a semipermeable membrane support was obtained. In addition, the surface which contacted the heating metal roll first was made into the application surface.

(Example 3-2)
A semipermeable membrane support was obtained in the same manner as in Example 3-1, except that the processing speed of the first stage and the second stage was changed to 10 m / min. In addition, the surface which contacted the heating metal roll first was made into the application surface.

(Example 3-3)
A semipermeable membrane support was obtained in the same manner as in Example 3-1, except that the processing speed of the first stage and the second stage was changed to 40 m / min. In addition, the surface which contacted the heating metal roll first was made into the application surface.

(Example 3-4)
A semipermeable membrane support was obtained in the same manner as in Example 3-1, except that the pressure of the first stage and the second stage was changed to 800 N / cm. In addition, the surface which contacted the resin roll first was made into the application surface.

(Example 3-5)
A semipermeable membrane support was obtained in the same manner as in Example 3-1, except that the pressure of the first stage and the second stage was changed to 1200 N / cm. In addition, the surface which contacted the heating metal roll first was made into the application surface.

(Example 3-6)
In the first stage, using a calender device that is a combination of a heated metal roll and a heated metal roll, the heated metal roll surface temperature is 230 ° C., the pressure is 1000 N / cm, and the processing speed is 30 m / min. Using the calender device of the combination of the second stage resin roll and the heated metal roll, except that the hot pressure processing was performed under the conditions of the heated metal roll surface temperature 150 ° C., the pressure 1000 N / cm, and the processing speed 30 m / min, A semipermeable membrane support was obtained in the same manner as in Example 3-1. Note that the surface in contact with the resin roll in the second stage was defined as the coating surface.

(Comparative Example 3-1)
In the first stage, using a calender device that is a combination of a heated metal roll and a heated metal roll, the heated metal roll surface temperature is 210 ° C., the pressure is 1000 N / cm, and the processing speed is 30 m / min. Using the calender device of the combination of the second stage resin roll and the heated metal roll, except that the hot pressure processing was performed under the conditions of the heated metal roll surface temperature of 150 ° C., the pressure of 1000 N / cm, and the processing speed of 30 m / min, A semipermeable membrane support was obtained in the same manner as in Example 3-1. Note that the surface in contact with the resin roll in the second stage was defined as the coating surface.

  Table 5 shows binder synthetic fiber content (%), melting point of binder synthetic fiber (° C.), combination of rolls in hot pressing (first stage) and hot pressing (second stage), kind of hot roll, half The surface temperature (° C.), nip pressure (N / cm), and processing speed (m / min) of the permeable membrane support were shown.

  For the semipermeable membrane supports obtained in the examples and comparative examples, the observation of the molten iron and the evaluation of the semipermeable membrane penetration, the semipermeable membrane adhesiveness and the semipermeable membrane surface observation were performed, and the results are shown in Table 6. Indicated.

  The semipermeable membrane supports of Examples 3-1 to 3-6 achieved very good levels in the semipermeable membrane penetration, semipermeable membrane adhesion, and semipermeable membrane surface observation. The length of the molten iron found in the semipermeable membrane support of Example 3-2 having a hot pressing speed of 10 m / min is as long as 150 μm, and between the fibers in which one molten iron constitutes the semipermeable membrane support. It was observed that several gaps were simultaneously crossed. In the hot-pressing process in the first stage, a semipermeable membrane support of Example 3-6 in which the surface temperature of the semipermeable membrane support is 227 ° C. using a calender device of a combination of a heated metal roll and a heated metal roll is Since the molten wrinkles generated on both surfaces in the first stage are laid down by hot-pressure processing in the second stage, the molten wrinkles lie on both the coated surface and the non-coated surface. It was very good, and the results were also very good in the evaluation of semipermeable membrane adhesion and semipermeable membrane penetration.

  Similar to the semipermeable membrane supports of Examples 3-1 to 3-6, the semipermeable membrane support of Comparative Example 3-1 contains main synthetic fibers having diameters of 7.5 μm and 12.5 μm. For this reason, the penetration of the semipermeable membrane was at a good level, but no melt defects occurred on both the coated and non-coated surfaces, so the semipermeable membrane adhesion was poor and practically unusable. It was. Further, when the surface of the semipermeable membrane was observed with a microscope, the main synthetic fibers penetrating the semipermeable membrane were found, which was a practically unusable level.

  The semipermeable membrane support of the present invention is used in fields such as seawater desalination, water purification, food concentration and wastewater treatment, medical fields represented by blood filtration, and ultrapure water production for semiconductor cleaning. Can be used.

Claims (9)

  A semipermeable membrane support comprising a nonwoven fabric comprising at least a main synthetic fiber and a binder synthetic fiber, wherein the binder synthetic fiber melt is present on at least one surface of the semipermeable membrane support. A permeable membrane support. 2. The semipermeable membrane support according to claim 1, wherein the number of molten defects observed in an electron micrograph of the surface of the semipermeable membrane support is 2 or more per 1.0 mm ² .   The semipermeable membrane supporting material according to claim 1 or 2, wherein a shape of the molten knot of the binder synthetic fiber is a branched shape.   The semipermeable membrane supporting material according to any one of claims 1 to 3, wherein a shape of the molten iron of the binder synthetic fiber is a shape in which a tip diameter of the molten iron is thinner than a diameter of the main synthetic fiber.   The molten soot crosses at least one kind of gap selected from the gap between the main synthetic fibers, the gap between the main synthetic fibers and the binder synthetic fibers, and the gap between the binder synthetic fibers. The semipermeable membrane support according to any one of claims 1 to 4, which has a shape.   The melted surface of the binder synthetic fiber is present on the coated surface, which is the surface on which the semipermeable membrane of the semipermeable membrane support is coated, and the molten surface of the coated surface is in a sleeping state. The semipermeable membrane support according to the description.   The semipermeable membrane support according to any one of claims 1 to 6, wherein melted soot of the binder synthetic fiber is present on both surfaces of the semipermeable membrane support.   A method for producing a semipermeable membrane support according to any one of claims 1 to 7, wherein a wet paper is produced by drawing up a slurry containing at least a main synthetic fiber and a binder synthetic fiber by a wet papermaking method. And a step of hot pressing the wet paper obtained in the previous step with a hot roll, and performing the hot pressing while confirming the surface temperature of the semipermeable membrane support immediately after the hot pressing. A method for producing a semipermeable membrane support.   Hot pressing so that the surface temperature of the semipermeable membrane support measured at a position less than 10 cm immediately after the nip after hot pressing is within the range of −65 ° C. to −20 ° C. with respect to the melting point of the binder synthetic fiber. The method for producing a semipermeable membrane support according to claim 8, wherein the surface temperature of the heat roll is set.